The objective of this study is to determine the relationship between structure, composition, and response to compressive loading in cortical bone at the osteonal level. Secondary objectives include the comparison of measured and predicted strain related potential production as a verification of structure/ property relationships and the projection of the models developed to larger sections of bone containing multiple structures. The central method of testing is the use of the microwave compressometer for mechanical characterization of viable Haversian osteon and pseudo osteon segments. Composition and structure are to be determined by a series of previously developed microchemical and optical methods. Completion of these studies, leading to an understanding of the intrinsic materials properties of cortical bone in vivo, will make possible the first stable in vitro tissue culture model of mature cortical bone and will lend to an extremely sensitive, early diagnostic technique for metabolic bone disease.